package linkedlist.leetcode_141;

public class Solution2 {
    public static boolean hasCycle(ListNode head) {
        if (head == null || head.next == null) {
            return false;
        }
        ListNode fast = head;
        ListNode slow = head;
        while (true){
            if(fast == null || fast.next == null) return false;
            fast = fast.next.next;
            slow = slow.next;
            if(fast == slow){
                break;
            }
        }
        return true;
    }
}
